The fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) introduces Internet gaming disorder (IGD) as a Substance-Related and Addictive Disorder in Section 3, Conditions for Further Study. Although research is in the nascent stages, existing studies demonstrate that IGD is associated with psychosocial distress including suicidality, and adverse vocational and educational outcomes in youth. Internet gaming disorder also shares substantial overlap with substance use, and it primarily affects adolescents, who rarely seek treatment on their own. Parents more often express concerns about their child's game playing behaviors, and data suggest that parents can have strong influences on it. This psychotherapy development study will evaluate feasibility, acceptability, and effect sizes of a behavioral intervention designed to help parents reduce gaming problems in their children. Sixty concerned parents and their children will complete parental and self-report inventories and structured diagnostic interviews regarding the child's gaming behaviors, substance use and psychosocial functioning. Participants will be randomized to either a control condition consisting of referral for mental health issues and family support services or to the same plus a 6-week family-based behavioral intervention designed to assist with better monitoring and regulating the child's game playing behaviors and encouraging and rewarding alternatives to game playing. Gaming and other problems will be assessed pre-treatment, mid-treatment, at the end of treatment, and at a 4-month follow-up. This study is unique in evaluating initial psychometric properties of a parental version of a measure that uses the DSM-5 criteria for IGD in a clinical sample, and it will also assess associations of IGD with substance use, psychological symptoms, and family functioning over time. Most importantly, this study will be the first randomized trial of an intervention designed to reduce gaming problems, and results are likely to guide future research and treatment efforts related to this condition